Current radio technologies such as LTE and LTE-Advanced (LTE-A) have been developed with maximum flexibility in mind in terms of deployment within the same radio technology. LTE and LTE-A are radio access technologies that provide a number of options for bandwidth utilization ranging from 1.4 MHz to 20 MHz per carrier (or per cell in 3GPP terminology) and duplexing distances (there are no tight dependencies on the duplex distance apart from being within a 100 kHz channel raster). In addition, both systems support both TDD and FDD modes of operation.
Furthermore, LTE and LTE-Advanced systems support deployment with frequency reuse 1, meaning that all neighbouring cells can use the same carrier frequency.
However, LTE and LTE-A have not been designed for ensuring a “natural migration path” for the physical layer. This means that network operators with limited spectrum resources currently used for existing radio technologies such as HSPA would need to either acquire new spectrum resources to introduce a new radio technology, or perform a “hard switch” between radio technologies. This would provide a number of current/legacy UEs with a significantly worse user experience, since part of the spectrum would be assigned to LTE, or even render them completely useless if the entire legacy spectrum were assigned to LTE.
Most modern communications networks are designed with very little or even no provision for ensuring a smooth transition path from previous/legacy systems to the new radio access technology.
The invention has been devised with the foregoing in mind.